Re: [PATCH v2 RESEND 2/3] mfd: atmel-hlcdc: fetch LVDS PLL clock for LVDS display

[<Manikandan.M@microchip.com>]

Hi Lee,

On 06/11/25 6:32 pm, Lee Jones wrote:
> EXTERNAL EMAIL: Do not click links or open attachments unless you know the content is safe
> 
> On Wed, 22 Oct 2025, Manikandan Muralidharan wrote:
> 
>> The XLCDC IP supports parallel RGB, MIPI DSI and LVDS Display.
>> The LCD Generic clock (sys_clk) is used for Parallel RGB and MIPI
>> displays, while the LVDS PLL clock (lvds_pll_clk) is used for LVDS
>> displays.Since both the clocks cannot co-exist together in the DT
>> for a given display, this patch first attempts to retrieve sys_clk
>> If that fails,it then tries to acquire lvds_pll_clk.
>>
>> Signed-off-by: Manikandan Muralidharan <manikandan.m@microchip.com>
>> Signed-off-by: Dharma Balasubiramani <dharma.b@microchip.com>
>> ---
>> changes in v2:
>> - Rephrase the comments, commit message and err logs
>> - Replace dev_err wwith dev_warn
>> - Remove Initializing sys_clk and lvds_pll_clk to NULL post
>> devm_kzalloc() call
>>
>> ---
>>   drivers/mfd/atmel-hlcdc.c       | 16 ++++++++++++++--
>>   include/linux/mfd/atmel-hlcdc.h |  1 +
>>   2 files changed, 15 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/mfd/atmel-hlcdc.c b/drivers/mfd/atmel-hlcdc.c
>> index 4c4e35d404f3..f680392b01ba 100644
>> --- a/drivers/mfd/atmel-hlcdc.c
>> +++ b/drivers/mfd/atmel-hlcdc.c
>> @@ -108,10 +108,22 @@ static int atmel_hlcdc_probe(struct platform_device *pdev)
>>                return PTR_ERR(hlcdc->periph_clk);
>>        }
>>
>> +     /*
>> +      * Retrieve any one of the Main clk required by the LCD to operate:
>> +      *
>> +      * LCDC Generic Clock (sys_clk) - Parallel RGB and MIPI displays,
>> +      * LVDS PLL (lvds_pll_clk)      - LVDS display
>> +      */
>>        hlcdc->sys_clk = devm_clk_get(dev, "sys_clk");
>>        if (IS_ERR(hlcdc->sys_clk)) {
>> -             dev_err(dev, "failed to get system clock\n");
>> -             return PTR_ERR(hlcdc->sys_clk);
>> +             dev_warn(dev,
>> +                      "failed to get LCDC generic clock, trying for LVDS PLL clock instead\n");
> 
> Does the user really care which clock they use?
> 
> Can this just happen silently instead?
> 
>> +             hlcdc->lvds_pll_clk = devm_clk_get(dev, "lvds_pll_clk");
>> +             if (IS_ERR(hlcdc->lvds_pll_clk)) {
>> +                     dev_err(dev, "failed to get LVDS PLL clock\n");
> 
> Failed to obtain both the LCDC (generic) and LVDS PLL clocks
> 
Thankyou, I will make sure v3 addresses these comments.

>> +                     return PTR_ERR(hlcdc->lvds_pll_clk);
>> +             }
>>        }
>>
>>        hlcdc->slow_clk = devm_clk_get(dev, "slow_clk");
>> diff --git a/include/linux/mfd/atmel-hlcdc.h b/include/linux/mfd/atmel-hlcdc.h
>> index 80d675a03b39..07c2081867fd 100644
>> --- a/include/linux/mfd/atmel-hlcdc.h
>> +++ b/include/linux/mfd/atmel-hlcdc.h
>> @@ -75,6 +75,7 @@
>>    */
>>   struct atmel_hlcdc {
>>        struct regmap *regmap;
>> +     struct clk *lvds_pll_clk;
>>        struct clk *periph_clk;
>>        struct clk *sys_clk;
>>        struct clk *slow_clk;
>> --
>> 2.25.1
>>
> 
> --
> Lee Jones [李琼斯]

-- 
Thanks and Regards,
Manikandan M.